Ketamine hydrochloride is a nonbarbiturate anesthetic chemically designated dl 2-(0-chlorophenyl)-2- (methylamino) cyclohexanone hydrochloride. It is formulated as a slightly acid (pH 3.5-5.5) sterile solution for intravenous or intramuscular injection in concentrations containing the equivalent of either 10, 50 or 100 mg ketamine base per milliliter and contains not more than 0.1 mg/mL Phemerol® (benzethonium chloride) added as a preservative. The 10 mg/mL solution has been made isotonic with sodium chloride.
DOSAGE AND ADMINISTRATION
Note: Barbiturates and ketamine hydrochloride, being chemically incompatible because of precipitate formation, should not be injected from the same syringe.
If the ketamine hydrochloride dose is augmented with diazepam, the two drugs must be given separately. Do not mix ketamine hydrochloride and diazepam in syringe or infusion flask. For additional information on the use of diazepam, refer to the WARNINGS and DOSAGE AND ADMINISTRATION Sections of the diazepam insert.
- While vomiting has been reported following ketamine hydrochloride administration, some airway protection may be afforded because of active laryngeal-pharyngeal reflexes. However, since aspiration may occur with ketamine hydrochloride and since protective reflexes may also be diminished by supplementary anesthetics and muscle relaxants, the possibility of aspiration must be considered. Ketamine hydrochloride is recommended for use in the patient whose stomach is not empty when, in the judgment of the practitioner, the benefits of the drug outweigh the possible risks.
- Atropine, scopolamine, or another drying agent should be given at an appropriate interval prior to induction.
Onset And Duration
Because of rapid induction following the initial intravenous injection, the patient should be in a supported position during administration.
The onset of action of ketamine hydrochloride is rapid; an intravenous dose of 2 mg/kg (1 mg/lb) of body weight usually produces surgical anesthesia within 30 seconds after injection, with the anesthetic effect usually lasting five to ten minutes. If a longer effect is desired, additional increments can be administered intravenously or intramuscularly to maintain anesthesia without producing significant cumulative effects.
Intramuscular doses, in a range of 9 to 13 mg/kg (4 to 6 mg/lb) usually produce surgical anesthesia within 3 to 4 minutes following injection, with the anesthetic effect usually lasting 12 to 25 minutes.
As with other general anesthetic agents, the individual response to ketamine hydrochloride is somewhat varied depending on the dose, route of administration, and age of patient, so that dosage recommendation cannot be absolutely fixed. The drug should be titrated against the patient's requirements.
Note: The 100 mg/mL concentration of ketamine hydrochloride should not be injected intravenously without proper dilution. It is recommended the drug be diluted with an equal volume of either Sterile Water for injection, USP, Normal Saline, or 5% Dextrose in Water